1. Field of the Invention
This invention relates to a surface mounting type electronic circuit unit.
2. Description of the Related Art
In general, a surface mounting type electronic circuit unit of this type has a structure in which various circuit parts are soldered on soldering lands of a conducting pattern formed on a substrate and these circuit parts are covered with a shield cover. The substrate has side end electrodes on the side thereof, and the side end electrodes are soldered on soldering lands of a mother substrate when the electronic circuit unit is surface-mounted on the mother substrate. The circuit parts used depend on the required circuit structure such as a tuning circuit, resonance circuit, or amplifier circuit. For example, the transistor, chip resistance, chip capacitor, and inductor are used as the circuit parts of an amplifier circuit, and these circuit parts are connected through the conducting pattern.
Recently, the technique for miniaturizing the circuit parts such as chip parts and transistor has been progressed markedly, and for example, the ultra-small chip resistor and chip capacitor having an apparent size of approximately 0.60×0.3 mm have been used practically. Therefore, it is possible that such small-size chip parts and transistor are used for the above-mentioned convention electronic circuit unit and are mounted on a substrate with narrow pitch between circuit parts to thereby miniaturize the electronic circuit unit to a certain extent. However, the miniaturization of the circuit parts such as chip parts and transistor is limited, and narrowing of the pitch between parts is limited because many circuit parts should be mounted on a substrate so that soldered portions of individual circuit parts are prevented from short-circuiting. These limitations have prevented further miniaturization of the electronic circuit unit.
Furthermore, in the case in which an electronic circuit unit of this type has, for example, an amplifier circuit and the emitter of a transistor for the amplifier circuit is grounded through a capacitor, a chip capacitor is soldered between a soldering land of a conducting pattern connected to an emitter electrode and a soldering land of a conducting pattern connected to a ground electrode in the above-mentioned conventional art. However, because the inductance of these two conducting patterns is not negligible, grounding is not sufficient and the interaction between the conducting pattern and chip capacitor causes parasitic oscillation disadvantageously.
The present invention has been accomplished in view of the above-mentioned problem of the conventional art, and it is the object of the present invention to provide a surface mounting type electronic circuit unit that is used suitably for miniaturization without parasitic oscillation.